1. Field of the Invention
The present invention is related to a valve or any other open and close apparatus and particularly to a position return device for an open and close apparatus.
2. Brief Description of the Related Art
In order to pursue fast speed and convenience, an open and close function of electrical actuation has been developed by the manufacturers for controlling ball valve, butterfly valve or other types of valves.
However, in case of the valves being required to shut urgently under a condition of emergency happening to power failure or power off accidentally, how to close the valves immediately is a problem bothering the manufacturers and the users. Besides, sometimes, the users desire to operate the valves manually but it is not possible for them to enter the shop to open or close the valves.